Gum Arabic Enhances Hair Follicle-Targeting Drug Delivery of Minoxidil Nanocrystal Dispersions

In this study, we attempted to enhance the delivery of minoxidil (MXD) nanocrystals into hair follicles for efficacious hair growth treatment. We applied a bead milling method and designed an MXD nanocrystal dispersion containing methylcellulose (MC) and gum arabic (GA), termed MG-MXD@NP, with a particle size of 110 nm. In vivo studies in C57BL/6 mice showed that MG-MXD@NP improved MXD delivery to the skin tissue, hair bulges, and hair bulbs, resulting in earlier and superior hair growth compared with a commercially available MXD lotion (Riup 5%, CA-MXD). These findings were consistent with the increased MXD contents observed in the hair bulge and hair bulb regions in the MG-MXD@NP-treated mice, and suggested a correlation between the efficiency of MXD delivery and efficacy of promotion of hair growth by products containing MXD. Furthermore, delivery of MXD using MG-MXD@NP was associated with elevated expression levels of CD34 and CD200, markers of hair follicle epithelial stem cells, which are crucial for promoting hair growth. Thus, it is possible that the upregulation of CD34 and CD200 in the MG-MXD@NP-treated mice reflects activation of the papilla cells and hair follicle stem cells known to be closely associated with hair growth enhancement. In conclusion, MG-MXD@NP, containing MXD nanocrystals in combination with MC and GA, exhibited a superior hair growth effect as compared with conventional MXD formulations. These findings suggest that this novel delivery method for MXD could represent a promising treatment approach for hair loss.